Dental instrument



Feb. 9, 1937. G. P. PHILLIPS DENTAL INSTRUMENT 2 Sheets-Sheet 1 FiledJune 7, 1934 Feb. 9, 1937. G. P. PHILLIPS DENTAL INS TRUMENT 2Sheets-Sheet 2 Filed June 7, 1954 Patented Feb. 9, 1937 UNlTED STATESPATENT OFFICE 12 Claims.

This invention relates to scientific instruments designed for use in thestudy of the physiology of the human jaws and teeth and their relationto each other.

Full chewing efficiency results from the coordination of the curvedocclusal tooth planes in correct relation to the forces exerted by thefuncticning muscles of mastication, and consequently many of theproblems with which the dentist must deal have to do with abnormalitiesin the anatomy or functions of the jaws and teeth. Mechanicallyconsidered, the human masticatory apparatus, when in function, moves inthree dimensions describing arcs within these dimensions from amultiplicity of centers of rotation. This invention aims to devise aninstrument with the aid of which these arcs or paths of movement may bedetermined and reproduced and which will facilitate the correction offunctional and anatomic abnormalities of the jaws.

The nature of the invention will be readily understood from thefollowing description when read in connection with the accompanyingdrawings, and the novel features will be particularly pointed out in theappended claims.

In the drawings,

Figure 1 is a plan view of an instrument constructed in accordance withthis invention;

Fig. 2 is a side elevation of the instrument shown in Fig. 1;

Fig. 3 is a sectional view through a portion of the instrument;

Figs. l and 5 are plan and sectional views illustrating a modification;

Figs. 6 and 7 are sectional views approximately on the lines 0 and 1-1,respectively, Fig. 1;

Fig. 8 is a front elevation of the parts shown in Fig. 3; and

Figs. 9 and 10 are horizontal and vertical sectional views,respectively, of the universal joint.

The instrument shown in the drawings comprises a stand 2 designed torest on a table or other suitable support. It includes a forwardlyprojecting arm which terminates in a clamp 3 designed to hold the lowerjaw cast. Mounted on the stand 2 is a carriage 4 provided with aforwardly extending arm 5 which carries an upper clamp B for holding theupper jaw cast. The carriage is mounted for floating or bodily movementin a horizontal plane and also for limited movement transversely to saidplane.

As above indicated, an important function of instruments of this type isto reproduce the relative movements of the jaws. These movements involvenot only forward, backward and lateral components, but also additionalcomponents in diagonal planes, and the extent and direction of suchmovements necessarily vary with different individuals. Consequently, toreproduce such movements accurately and in the ranges necessary toaccommodate the great variety of conditions found in patients, is animportant functicn of this instrument. This requirement introducesunusual problems in the relative guiding of the jaw casts.

The guiding mechanism for the carriage 4 comprises two upright pinsindicated, respectively, at l and 7, both secured rigidly to the upperhorizontal arm of the carriage, and equally spaced laterally from thelongitudinal median plane of the instrument. Both pins rest on rockingplanes, each of which may be tipped forward, backward, or laterally,theoretically into an infinite number of vertical planes, allintersecting the axis of its respective pin. Since the rocking planesfor the two pins are duplicates one of the other, a description of oneonly need be given. Referring more especially to Figs. 2 and 3, it willbe seen that the rocking plane 8 for the pin 7 consists of a section ofa sphere having an approximately fiat upper surface on which the ballend of the point of the pin 1 rests. While said upper surface can be aplane, it is preferable to make it very slightly concaved, the degree ofconcavity being somewhat exaggerated in the drawings. For practicalpurposes this entire guiding surface may be regarded as locatedapproximately in a plane bisecting the sphere, the center of the spherenormally lying in the axis of the pin 1. This hemispherical member 8,which usually is referred to as a rocking plane, or as the horizontalrocking plane, is mounted in a tapered socket 9 formed in a portion ofthe stand 2, or more conveniently in a bushing ll threaded into the arma of the stand 2, the socket being of frusto-conical form.

For the purpose of adjusting the rocking member 8 and holding it in anyposition to which it may be adjusted, a stem 10 is secured rigidly in itand projects downward radially therefrom through av slide or plate l2with Which the stem has a sliding fit. The connection between the stemand the slide preferably includes a ball I3 through which the stemslides, the ball having a rotary fit with the slide 12 but being heldagainst it by a spring I5 which encircles the stem l0 and bears at itsupper end against the ball and at its lower end against a handle l6threaded on the lower end of the stem. The slide I2 is mounted to run inguideways formed in a second slide I! which is mounted to slide in adirection transverse to the direction of the sliding movement of thepart l2, the slide l1, however, carrying the slide i2. By moving thehandle l6, therefore, the plane 8 may be rocked in its socket into anyone of a multitude of vertical planes, each intersecting the center ofthe member 8. It can also be swung into any one of a great variety ofangular positions in any selected one of said vertical planes. Duringsuch movements the spring I5 holds the member 8 bottomed in its socket.The two slides I2 and I? serve to resolve the movements of the rockingmember into its two horizontal components. Consequently, by suitablygraduating these slides or parts adjacent to them, and associatingpointers with them, an accurate designation of any adjustment of themember 8 may be made. As shown in'Fig. 2, the edge of the slide I1 isgraduatedin degrees and a pointer l8, Fig. 8, secured to the slide I2 isarranged to run along the lower edge of said graduations as the slide ismoved. Another scale, similarly graduated, is secured to the front faceof the slide I I, as shown in Fig. 8, and cooperates with a center markon a stationary part of the instrument to designate the adjustment ofthe slide I! in either direction away from its central position. A thumbscrew I9, Figs. 1, 3 and 8, is threaded through a portion of the slideI! and is arranged to bear against a stationary part of the instrumentto lock this slide in its adjusted position, while another thumb screw28 is threaded through the slide I! and is arranged to engage the edgeofthe plate I2 to lock the latter in its adjusted location.

Parts corresponding to those cooperating with the pin I are provided tocooperate with the other pin 1' at the opposite side of theinstrument,and these parts have been designated by corresponding, butprimed, numerals. With this arrangement, therefore, it is a simplematter for the user of the instrument to adjust the planes into thepositions necessary to suit the requirements of any individual case, tomake a record of those positions, and thereafter to reproduce the sameadjustment with a high degree of accuracy.

The planes 8 and 8' determine the plane of the path of movement of thecarriage, or, in other words, the angular relationship of said path to ahorizontal plane. In order to guide the carriage along the desired pathor paths in a horizontal plane or in any plane of inclination determinedby the members 88', a pair of circular plates, each provided with aknife edge, is arranged to engage the stem I immediately above the plane8. As shown in Figs. 1 and '7, these two plates 2| and 22, respectively,are mounted one above the other in a circular holder 23 which is setinto the arm b integral with the stand 2. Two small bolts 24, 25, Fig.7, secure the holder in a fixed, stationary position and hold the platesin the part 23. Both of the circular plates 2| and '22, however, arefree to be rotated within the holder 23 and they may be selectivelylocked in their adjusted positions by thumb screws 24 and 25,respectively. These two plates thus may be adjusted so that their knifeedges, which engage the stem 1, will define any one of a great varietyof angular paths in which the stem can be guided while its lower endrides over the surface of the rocking plane 8. A scale 26, Fig. 1,engraved on the edge of the holder 23, cooperates with pointers 21 and28, Fig. 7, on the respective plates, to designate the angular positionsof the plates for convenience in making a record of the setting requiredfor any individual case. The various parts above described whichcooperate with the pin I are duplicated at the other side of the machineto co-a-ct in the same manner with the pin 7.

It is of advantage to be able to rotate the member 8 around the axis ofthe spindle, together with the slides I2 and I1, while maintaining therelationship of the member 8 to the slides undisturbed. An arrangementsuitable for this purpose is illustrated in Figs. 2, 3 and 8 in which anintermediate member 29 is secured to the lower face of the arm a by thesocket member a II. This socket member is made of circular outline andis flanged to receive and hold the part 29, while the latter is groovedto support the slide IT. The second slide I2 is carried by the firstslide as above described. This arrangement, however, permits therotation of the part 29, with the slides mounted on it, about the axisof the pin 7 without disturbing the adjustment of the member 8. Normallythe member 29 is locked in a stationary position by means of a thumbscrew 38, Figs. 2 and 8, threaded through the arm a and bearing againstthe upper surface of the member 29. A scale 3I-, Figs. 2 and 8, securedto the forward curved end of the arm a cooperates with a center mark 32,Fig. 8, on the intermediate member 29 to designate the degree of angularadjustment of the latter member.

In some instruments which do not require the refinements of theinstrument shown in Figs. 2 and 3, a simpler arrangement for supportingthe rocking planes may be used. One such construction is illustrated inFigs. 4 and 5-and comprises a rocking plane 34, similar to the member 8,supported in a hemispherical socket formed in the upper surface of asocket member 35 which is mounted on a suitable stand 36. Adjustment ofthe member 34 into any desired angular position may be made by suitablymanipulating screws 31. 38 and 39 located apart around the margin of therocking member 34. As shown in Fig. 5, the screw 31 is held againstvertical movement and is threaded through a slide 40 which runs in avertical guideway and carries a finger 4| arranged to bear against theedge of the rocking member 34. Each of the other screws 38 and 39 arelikewise connected with similar fingers 42 and 43, so that by properlymanipulating the three screws the member 34 may be adjusted into anyangular position within the limits of this construction. The degree ofadjustment so produced can be measured by suitable graduations on theedges of the guides for the slides, or, by making two semicircular rowsof graduations, each on great circles of the hemispherical socket inwhich the member 34 rocks, these two circular lines of graduations beingat right angles to each other.

For the purpose of reproducing relative retrusive and protrusivemovements and opening and closing movements of the jaws without the lossof normal relations, a post 45, Figs. 1, 2 and 6, is fixed rigidly inthe. frame or stand 2 and a ball 46 is slidably mounted on it, this ballbeing received in a tubular extension 41 projecting rearwardly from thecarriage 4. Preferably this extension is a separate piece from thecarriage and is provided at its forward end with a horizontallyflattened end face to fit against a similar face of the carriage. Theseparts are secured together by a pivot screw 58, thus providing a jointwhich permits relative lateral movement between the main part of thecarriage and the extension 41. A thumb screw 5I, threaded on the screw50 looks both of these parts rigidly together, when desired.

The extension 41 can slide freely backward and forward on the ball 46,and the ball can be moved with the extension up and down on the post 45,the upper limit of this movement being predetermined, when desired, bymeans of a thumb nut 53 threaded on to the post.

This ball may also be used conveniently as a stop in producing therelative protrusive and retrusive movements of the dentures. As shown inFig. 6, a spring 52 is enclosed in the tubular extension 4'! and abutsat one end against a plate 56, slidable in said extension, and at itsopposite end against the end of the bore in said extension.Consequently, this spring tends to force the ball and the carriageapart, and thus to maintain the inner end of the screw 57 against theball. The screw itself does not directly engage the ball but it carriesan internal screw 58 which does bear against the ball. However, thisinner screw 58 is used only in making the initial adjustment andthereafter turns with the screw 51 so that so far as the normalfunctional movements of the screw 51 are concerned, the member 58 is apart of it. It will be evident from an inspection of Figs. 2 and 6 thatif the screw 57 is turned inwardly it will act against the ball 46 as astop to draw the entire carriage and the upper jaw cast backwardly, thusproducing a relative protrusive movement of the lower jaw. If a scale.such as that illustrated at 6| in Fig. 1 is operatively associated withthis screw, the extent of the said protrusive movement may be measured.It will also be evident that if the screw 51 is backed up, it willpermit the entire carriage and the upper denture to slide forwardly andsuch a sliding movement will be produced by the spring 52 whichserves tohold the plate 56 constantly against the ball 46. The extent of thismovement can also be measured on such a'scale as that shown at 6|, Fig.1.

Frequently it is important in making these movements to be able to comeback quickly to a zero position. This position may conveniently be fixedby means of a spring pressed pin 62, Fig. 6, slidable freely in aportion of the extension 41, the lower end of this pin being adapted toenter a hole drilled radially in a smooth or non-threaded part of thescrew 51. The initial zero adjustment is made with the pin 62 lookingthe screw 51 against rotation, as shown in Fig. 6, and then turning theinner screw 58 inward or outward, as desired, until the carriage isbrought into its central or zero relationship to the stationary parts ofthe instrument. This screw 5'! then is locked in its adjusted positionby means of a set screw.

: Thereafter the screw 51 may be freed from the locking pin wheneverdesired by lifting the latter and the end of this pin will simply rideon the smooth unthreaded portion of the screw until the latter isbrought back again to its zero position.

When it is desired to make the movements of the carriage as free aspossible, the plate 56 may be moved forward to compress the spring 52,after which its ends, which are relatively narrow and flat, are forcedinto notches 63, which look the plate and thus hold the spring in acompressed condition. Several pairs of these notches provide for thelocking of this plate in different positions.

It will be observed that in this instrument the movements of thecarriage, and consequently of the upper jaw cast, are guided by theengagement of the lower ends of the pins 1 and l with the horizontalplanes 8 and 8. Since these rocking planes can be adjusted into ahorizontal plane or any angle of inclination (within the limits of theinstrument) with reference to such a plane, an almost infinite varietyof angular paths of movement may be produced. The direction of anydesired path may also be predetermined by properly adjusting the knifeedges 2| and 22 and 2| and 22', all of which can be moved through arange of 360. Consequently, the relative movements in three dimensionsmade by the jaw can be reproduced with a high degree of accuracy. Inaddition, the protrusive and retrusive movements can be closelysimulated. In opening the bite the tipping movement of the carriage isguided partly by the movement of the ball 46 on the post 45 and partlyalso by the contact of the lower ends of the pins 1 and I with therocking planes 8 and 8. Also, the carriage can be freed from anysubstantial drag of the extension 47, when desired, by compressing andlocking the spring 52 and loosening the thumb nut 5|. The wide range ofmovement thus provided in this instrument greatly facilitates the studyof anatomic and functional abnormalities of the jaws and teeth andenables the dentist to reproduce faithfully the conditions peculiar toindividual cases.

Preferably the upper arm 5 is hinged to the carriage 4 by the thumbscrew 65 so that it can be swung upwardly, whenever desired, relativelyto the carriage or may be locked rigidly to the latter.

A novel form of clamp for securing the jaw casts in position isprovided, that for the upper cast comprising three threaded rods 66, 61and 68, all pivoted independently between the collars 68 of the upperclamp 6 to swing around the axis of the clamp. On each rod is a slide 10carrying two pins which project downwardly therefrom and serve to engagethe sides of the cast and each slide is backed up by a screw H whichserves to force it inwardly against the cast or to release it to permitthe removal of the cast. The lower clamp is of essentially the sameconstruction.

Preferably the upper clamp 6 is secured to the arm 5 by a universaljoint which permits adjustment of the upper clamp in any direction in ahorizontal plane relatively to the arm as well as rocking or angularadjustments. This joint construction is best shown in Figs. 2, 9 and 10.As

there illustrated, the clamp is mounted on the lower end of a verticalrod H which passes through a split ball 12. This ball is held betweenupper and lower socket members 13 and 14, respectively, having sphericalsurfaces to engage the ball, and these socket members, in turn, aremounted in a holder which includes a cylindrical extension [5 integralwith and projecting downwardly from the arm 5 and a collar 16 threadedon said extension. It will be observed that the holes in the arm 5 andcollar 16 through which the rod or stem H projects are relatively largeso that they permit a considerable movement of the stem relatively tothe arm in any direction in a horizontal plane and also provide for aconsiderable rocking movement of the stem about the center of the ball12. The upper clamp 6 is rigidly secured to the stem and consequentlymoves with it. This arrangement, therefore, provides for the movement ofthe upper clamp and the jaw cast secured in it into variousrelationships to the lower east. When it has been moved into itsadjusted position it can be clamped by turning up the threaded collar16. In addition, a nut 11 is threaded onto the upper end of the stem Hand provides for the vertical adjustment of the clamp 6 and the upperjaw cast relatively to the arm 5.

While I have herein shown and described a preferred embodiment of myinvention, it will be understood that the invention may be embodied inother forms without departing from the spirit or scope thereof.

Having thus described my invention, what I desire to claim as new is:

1. In an instrument of the character described, the combination of astand, a carriage mounted on said stand for floating movement insubstantially any direction in a horizontal plane and for additionalmovement away from said plane, means for fastening a cast to saidcarriage, means for guiding said carriage comprising two pins secured tosaid carriage and spaced apart, two rocking hemispherical members eachprovided with a substantially fiat upper surface for supporting saidpins, respectively, for movement on said surfaces, means provided withsockets supporting each of said members for tipping adjustment in anyvertical plane intersecting said surfaces of the respective rockingmembers, and additional means cooperating with said rocking members toengage and guide said pins in the desired paths as said pins are movedon the surfaces of said rocking members, said additional means beingadjustable to vary the direction of said paths, as desired.

2. An instrument according to preceding claim 1, characterized by thefact that said additional means for guiding each pin comprises a pair ofstraight edged plates, and means for supporting said plates foradjustment about approximately the axis of the pin which they guide toform an angle along the edges of which the pin can. move.

3. An instrument according to preceding claim 1, characterized by thefact that said additional means for guiding each pin comprises a pair ofstraight edged plates, means mounted on said stand for supporting saidplates for adjustment around the axis of said pin into any angularposition within a range of substantially 360, and scales associated withsaid plates for designating their angular positions.

4. An instrument according to preceding claim 1, comprising a stationarypost mounted on said stand at the rear of the vertical plane connectingsaid pins and approximately midway between said rocking planes, anextension projecting rearwardly from said carriage and cooperating withsaid post to guide the carriage, a joint connecting said carriage withsaid extension and permitting relative lateral movement between saidcarriage and said extension, and means for lock ing said extensionrigidly to said carriage when desired.

5. An instrument according to preceding claim 1, comprising a stationarypost mounted on said stand at the rear of the vertical plane connectingsaid pins and approximately midway between said rocking planes, atubular extension projecting rearwardly from said carriage, a ballslidable on said post and positioned in said extension, a spring locatedin said extension and tending to force said carriage and ball away fromeach other, and screw threaded adjusting means for engaging the side ofsaid ball opposite to said spring and cooperating'with said ball toadjust the position of said carriage in the desired forward and backwardrelationship.

6. In a dental articulator, the combination with a stand, a carriagemounted on saidstand for bodily movement in substantially any directionin' a horizontal plane and for limited movement transversely to saidplane, and means for fastening a cast to said carriage, of means forcontrolling the movements of said carriage comprising a rocking memberhaving a shape substantially like that of a section of a sphere andprovided with an approximately fiat upper surface, a support having asocket in which said member is mounted for substantially universaltipping movement around the center of said sphere, and means operable toadjust said member into any of its various angular positions.

'7. In a dental articulator, the combination with a stand, a carriagemounted on said stand for bodily movement in substantially any directionin a horizontal plane and for limited movement transversely to saidplane, and means for fastening a cast to said carriage, of means forcontrolling the movementsof said carriage comprising a rocking memberhaving a shape approximately like that of a section of a sphere andprovided with an approximately fiat upper surface, a support having asocket in which said member is mounted for substantially universaltipping movement about the center of said' sphere, and two horizontalslides operatively connected with said member and movable transverselyto each other for indicating variations in the positions of adjustmentof said member about said center.

8. An instrument according to preceding claim 6, characterized by thefact that the socket in' which said member is mounted is tapered aboutan axis passing substantially through the center of said member.

9. An instrument according to preceding claim 6, in which said adjustingmeans comprises a stem extending radially from said rocking mem ber, aslide through which said stem projects, and a ball guide for said stemmounted in and movable with said slide.

10. An instrument according to preceding claim 6, in which saidadjusting means comprises a stem extending radially from said rockingmember, a slide through which said stem projects and with which it has asliding fit, whereby said member may be angularly adjusted by movingsaid slide, and means cooperatively associated with said slide toindicate the angular positions of said member.

11. An instrument according to preceding claim 6, in which saidadjusting means comprises a stem extending radially from said rockingmember, a slide through which said stem projects and with Which it has asliding fit, whereby said member may be angularly adjusted by movingsaid slide, a second slide mounted on said stand for movementtransversely to the direction of sliding movement of the first slide,the first slide being carried by said second slide, the upper surface ofthe first slide being graduated, and a pointer associated with saidgraduations to indicate the angular positions of said rocking member.

12. An instrument according to preceding claim 6, in which saidadjusting means comprises a stem extending radially from said rockingmember, a slide through which said stem projects and with which it has asliding fit, whereby said member may be angularly adjusted by movingsaid slide, a second slide mounted on said stand for movementtransversely to the direction of sliding movement of the first slide,the first slide being carried by said second slide, and means forsupporting both of said slides on said stand for rotary adjustmentaround the center of said rocking member.

GEORGE P. PHILLIPS.

